1. Field of the Invention
The present invention generally relates to printing devices and, more particularly, to a printing device for printing adhesive labels and the like having a continuous belt system for transporting the labels through printing assemblies of the printing device.
2. Discussion of the Related Art
In typical label printing devices, labels having a pressure-sensitive adhesive are serially mounted on a roll which typically consists of a media web of paper or plastic film. The roll is mounted on a payoff roller of the printing device and the web including the labels mounted thereon is threaded through the printing assemblies of the printing device to enable the printing assemblies to print on each label as it passes therethrough. The web is pulled through the printing assemblies by a series of pinch rollers located along the feed path. After passing through the printing assemblies and pinch rollers, the web is fed out of the printing device and either re-rolled onto a take-up roller or the label is manually peeled of the web as it exits the printing device for immediate application to a product which the label is to identify.
However, it has been found that the quality of the printing performed by the above-described printing apparatus can be adversely affected as the web is pulled through the printing device. Since the pinch rollers must contact the labels immediately after they are printed on, there is a potential for the rollers smudging or otherwise affecting the print quality. Moreover, since the labels are fed through the printing assemblies on the media web, any inconsistencies in the web or in the speed at which the web is pulled can cause problems in the printing process. For example, any slack in the web will adversely affect the contact between the printing head and the label and any slippage between the pinch rollers and the media web will cause smudging in the printing process. Furthermore, since the labels are typically mounted on a wax paper-type printing media, any wrinkles or other inconsistencies in the media web can adversely affect print quality and can also cause the web to break as it is pulled through the printing apparatuses, thus causing downtime of the printing device and requiring that the web be rethreaded through the printing apparatuses.
Another disadvantage of the prior art system is the inability to print individual labels on demand or to vary the speed or frequency at which labels are printed. Since the labels are pulled through the printing apparatuses while being mounted on the media web, the labels can only be printed at a single speed which is determined by the spacing of the labels on the media web as it is passed through the printing assemblies. Furthermore, if it is desired to print only one label, the label must be fed through each printing assembly and peeled off of the media web, which them must be pulled back through each printing assembly in order to line up the next label to be printed on with the first printing assembly. This process is very time consuming and complicated.
What is needed is a printing device which includes a discrete carrier belt which serially receives the labels as they are peeled from the media web and transports the labels through the printing assemblies without the use of pinch rollers which can adversely affect the print quality of the printing device. The carrier belt will provide a more durable and consistent platform on which the labels are transported through the printing assemblies. The device would also be capable of printing labels at varying speeds and frequencies and printing one label at a time without the need for backing the media web through the printing assemblies.